Circular stapler buttress

ABSTRACT

A buttress for use with circular surgical staplers that does not require adhesive to securely fasten the buttress to the stapler and that self-aligns onto the stapler. Following cutting and stapling by the circular stapler, the buttress has an adaptive opening through its central region with a diameter smaller than the outer diameter of the stapler anvil. Because of relief features built into the buttress, the stapler anvil may be pulled through the buttress material without causing permanent alteration to the buttress. These relief features may be provided regardless of whether the buttress is made of inelastic or elastic materials. The buttress is generally circular in shape with an outer diameter sized to coincide with the outer diameter of the stapler body staple compression surface and the outer diameter of the anvil compression surface of a circular stapler with which it is used. Prior to surgical use, the buttress is provided with a generally circular hole in the central region that is sized to closely fit the central shaft of a circular stapler with which it is used.

FIELD OF THE INVENTION

The present invention relates to the field of surgical buttresses.

BACKGROUND OF THE INVENTION

A circular stapler is one device that can be used in surgicalapplications for the joining of body tissue. In the area of surgicalanastomotic stapling, it can be used for joining pieces of tissue in amanner such that a continuous pathway, lumen, or surgical opening, isformed after the tissue is stapled together. This lumen is formed when acircle of staples is used to join two pieces of tissue after which thetissue interior to the innermost circle of staples is cut out by aconcentric circular retractable blade. Retraction of the circularstapler removes the cut tissue to form a lumen. An example of a circularstapler is given in U.S. Pat. No. 5,104,025 to Main et al. Other devicesand methods can also be used to produce anastomoses.

When used in surgery for colorectal disorders the circular stapler isused to reform the colon into a continuous lumen after a section isremoved for treatment of the disease state. Concerns about leakage ofthe colon contents into the peritoneal cavity from the anastomosis siteare prevalent during this type of surgery. A complete seal between thepieces of tissue that are joined is desirable to prevent leakage.Another concern in colon resections is reduction of the lumen diameterafter surgery. This reduction in diameter would result in therestriction of the passage of biological material.

Using a stapler that forms a lumen with a diameter close to that of thepreoperative healthy colon is desirable to prevent these flowrestrictions. Typically the circle of staples formed is between 2-4 cmin diameter and is made from 20 to 40 small, metallic staples. Due inpart to the presence of these metallic staples, another concern intissue resection is tearing of the tissue at the anastomosis site.

Modifications to circular staplers as well as the development of otherdevices have been described to address the concerns that may occurduring stapling of body tissue and the formation of a tissueanastomosis. A device used to create an anastomosis without staples isdescribed in U.S. Pat. No. 5,222,963 to Brinkerhoff et al. and U.S. Pat.No. 5,250,058 to Miller et al. This device uses a tissue coupler madefrom a bioabsorbable polymer. A concern in using this device is the riskof tissue separation at the anastomosis site after the polymer has beenabsorbed by the body. A similar concern is shared for the devicedescribed in U.S. Pat. No. 5,346,501 to Regula et al., as it also usesonly a bioabsorbable material for the formation of the anastomosis.

To alleviate the concern about tissue separation after the absorption ofa bioabsorbable material, non-absorbable biocompatible metal staples canbe used to form the anastomosis. However, leakage and/or tearing at thesite where the tissue is joined are concerns when only metal staples areused. In order to prevent leakage or tearing, supporting buttressesconstructed of both non-bioabsorbable and bioabsorbable materials foruse with surgical staplers have been described in various publications.U.S. Pat. No. 6,503,257 to Grant et al. teaches a method for using anadhesive to releasably attach a buttress construct to a surgicalstapling instrument. This buttress addresses both the leakage andtearing concerns that occur during tissue stapling. The use of metalstaples provides for the long-term joining of the tissue. However, thebuttress must be carefully aligned onto the stapling instrument and asuitable adhesive must be used on the surfaces of both the buttress andthe stapling instrument to secure the buttress to the staplinginstrument. Further, withdrawing the anvil part of the stapler throughthe buttress may be difficult, as the inner diameter of the buttress issmaller than the outer diameter of the stapler anvil.

SUMMARY OF THE INVENTION

The present invention is in the form of a buttress reinforcement devicefor use with circular surgical staplers that does not require anadhesive substance between the buttress and stapler to securely fastenthe buttress to the stapler. Preferably, the buttress self aligns ontothe stapler. In a preferred embodiment, when used with a circularsurgical stapler, a hole is cut in the central region of the buttress bythe stapler's circular cutting blade. The diameter of the hole formed inthe buttress by the stapler's circular cutting blade is smaller than theouter diameter of the stapler's anvil. Relief features built into thebuttress allow the stapler anvil to pull through the hole created in thebuttress by the stapler's circular cutting blade without causingsubstantial permanent alteration to the buttress. These relief featurescan be provided regardless of whether the buttress is made of inelasticor elastic materials.

The buttress can be generally circular in shape with an outer diametersized to coincide with the outer diameter of the stapler body staplecompression surface and the outer diameter of the anvil compressionsurface of a circular stapler with which it is used. Alternatively, thebuttress material may be formed into other non-circular geometric shapes(e.g. octagons). Also, the buttress material can be sized to be largerthan or the same as the outer diameter of the stapler body staplecompression surface and the outer diameter of the anvil compressionsurface of a circular stapler with which it is used in order to allowfor self-alignment. This self-alignment insures that the buttress isaligned to coincide with and cover the pattern of staples ejected fromthe stapler. The buttress may have a generally circular opening in itscentral region that is sized to closely fit the central shaft of acircular stapler with which it is used. Alternatively, the buttress mayhave slits or other openings cut in its central region to allow forfitting the buttress onto the central shaft of a circular stapler whileretaining the self-alignment feature. In a preferred embodiment, thecentral region of the buttress is that area which is cut away from thebuttress by the action of the stapler cutting blade. In addition to thecentral opening, the buttress may have a slit or other opening reachingfrom the central opening to the outer diameter of the buttress. Thisfeature would allow the buttress to be placed onto the central shaft ofa circular stapler even when the stapler anvil was already attached tothe stapler body through the central shaft.

In one embodiment, the buttress can have a retaining ring, disk, orsimilar device within or around its central region with a centralopening. This retaining ring, disk, or similar device can be used to aidin the retention of the buttress onto the central shaft of the circularstapler without requiring the use of an adhesive substance between thecentral shaft of the stapler and the buttress construct. The retentionof the buttress onto the circular stapler allows for movement, removal,or repositioning of the circular stapler during operation without lossor displacement of the buttress from the stapler.

A preferred bioabsorbable buttress is fabricated from a copolymer ofpoly(glycolide:trimethylene carbonate). The copolymer's polyglycolidecomponent is commonly abbreviated as PGA for poly(glycolic acid), thechemical byproduct to which it degrades after hydrolysis. Thepoly(trimethylene carbonate) component is commonly abbreviated as TMC,with the copolymer itself typically referred to as PGA:TMC andaccompanied with relative percentage composition by weight. A preferredembodiment of the buttress is made from a bioabsobable ABA triblockcopolymer of 67% PGA:33% TMC (w/w), formed into a non-woven web astaught by Hayes in U.S. Pat. Nos. 6,165,217 and 6,309,423. Otherfabrications, processes, and polymers can alternatively be used toproduce an elastic bioabsorbable buttress, such as using the polymersdescribed by Bezwada in U.S. Pat. Nos. 5,468,253 and 5,713,920. Whilethe primary constituent polymer can be alternatively blended with otherpolymers or active or inactive agents prior to fabrication, theresulting buttress can be imbibed, coated, or otherwise loaded withtherapeutic or other either bioactive or bioinactive materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective views of the bioabsorbable circularstapler buttresses mounted on a typical circular stapler and showing howthe anvil portion of the circular stapler can be separated from the bodyof the stapler.

FIGS. 2A-2D are cross sectional views of colon undergoing resectionusing the buttresses of the present invention.

FIG. 2E is a perspective view of a longitudinal section of a colonundergoing resection using buttress of the present invention, that hasbeen cut and stapled by a circular stapler.

FIGS. 3A-3F show top views of various embodiments of the buttress.

FIGS. 3G, 3H, 3J and 3K show perspective views of the buttress havingvarious corrugations.

FIGS. 4A-4C show side views of three alternate embodiments of thebuttress with varying thicknesses and densities.

FIGS. 5A-5E show top views of elastic and inelastic buttresses prior toand following central region cut out by the generally circularconcentric cutting blade of a circular stapler and following removal ofthe anvil portion of a circular stapler through the central region hole.

FIG. 5G shows a cross sectional view of an inelastic buttress followingremoval of the anvil portion of a circular stapler though the holecreated by the generally circular concentric cutting blade of a circularstapler.

FIG. 6A shows a perspective view of a buttress allowing forself-alignment on the central shaft of a circular stapler.

FIG. 6B shows a cross sectional view of a buttress allowing forself-alignment on the central shaft of a circular stapler.

FIG. 6C shows a perspective view of a buttress allowing forself-alignment on the outer diameter of a stapler anvil head or staplerbody compression surface.

FIG. 6D shows a cross sectional view of a buttress allowing forself-alignment on the outer diameter of a stapler anvil head or staplerbody compression surface.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a typical circular surgical stapler 10with two stapler buttresses 12 mounted on the central shaft 14 of thestapler. The stapler has an anvil head 16 with a staple compressionsurface 18. The anvil head 16 is removably attached to the stapler body22 via the central shaft 14 as shown in FIG. 1B. The stapler body alsohas a compression surface 20 through which staples are ejected. Thecentral openings 15 in the buttresses 12 are sized to closely fit overthe central shaft 14 so that the buttresses self-align onto the shaft.The central openings 15 in the buttresses 12 may be generally circular,slits or of any other geometric shape. Because of the size and shape ofthe central openings 15, the buttresses 12 are self-aligned andconcentric to the cutting mechanism and stapler compression surfaces ofthe circular stapler. Each buttress 12 further has a member 13 that aidsin attaching the buttresses 12 to the central shaft 14 of the staplerwithout the use of adhesive substance between the central shaft 14 ofthe stapler and the buttresses 12. The buttresses 12 can be placed ontothe central shaft 14 of the circular stapler 10 when the stapler anvil16 is separated from the stapler body 22 as shown in FIG. 1B.Alternatively, a buttress 12 with a slit or other opening reaching fromthe central opening to the outer diameter of the buttress can be placedonto the central shaft 14 of a circular stapler 10 when the stapleranvil 16 is connected to the stapler body 22 as shown in FIG. 1A.

FIGS. 2A-2E show circular stapler buttresses 12 in use during, forexample, a typical colon resection. FIG. 2A shows the stapler anvil head16 and a buttress 12 placed inside the proximal end of a colon section24, wherein proximal is defined as being closer to the heart of thepatient being operated upon. An end of the central shaft 14 isprotruding through a hole 29 formed in the colon tissue wall 25. Thestapler body 22 and another buttress 12 are placed transanally inside adistal segment of the colon 26, wherein distal is defined as beingfarther from the heart of the patient being operated upon. Another endof the central tubular shaft 14 protrudes through a hole 31 formed inthe distal colon tissue wall 27.

FIG. 2B shows the central shaft 14 with the anvil head 16 now joined tothe stapler body 22. One buttress 12 is located between anvilcompression surface 18 and the proximal colon tissue wall 25. Anotherbuttress 12 is located between the body compression surface 20 and thedistal colon tissue wall 27. The circular stapler 10 can be operated soas to pull the anvil head 16 towards the stapler body 22 so that theanvil head 16 and stapler body 22 are moved to within close oppositionof each other.

FIG. 2C shows the anvil head 16 and stapler body 22 in close proximityto each other in a position where the staples can be ejected through thecompression surface on the stapler body 20 to pierce through theopposing tissue walls of both the proximal 25 and distal 27 colon wallsections and also though the buttresses 12 placed internally within eachcolon section. The staples upon ejection are bent as they impact on thecompression surface 18 of the anvil head 16 and compression surface 20of the stapler body 22, to form a shape designed to tightly hold thecolon sections together. The staples pierce through the colon tissuewalls 25, 27 and the buttresses 12 that are placed internally on eachside of the joined colon sections. FIG. 2C also shows a generallycircular concentric cutting blade 33 which can be actuated by thestapler operator when the stapler anvil head 16 has been moved to aposition of close opposition to the stapler body 22. The generallycircular concentric cutting blade 33 in the circular stapler body 22moves upon actuation by an operator from a retracted position to anextended position to cut through the opposing walls of both the proximal25 and distal 27 colon sections as well as the buttresses 12 placedinternally in each colon section after the staples have been positionedand ejected. The generally circular concentric cutting blade cutsthrough the tissue adjacent to the inner diameter of the innermost rowof staples to allow a continuous lumen to form between the now-joinedcolon sections. Therefore an anastomotic junction is created in the bodytissue. After the anastomotic junction has been formed, the stapler isoperated so that the stapler anvil head 16 is moved away from the staplebody 22 to release the tissue compressed between the compressionsurfaces of the anvil head 18 and stapler body 20. The circular stapler10 is withdrawn transanally carrying with it the sections of colontissue and central regions of the buttresses 12, which were cut by thegenerally circular stapler blade.

FIGS. 2D and 2E show the proximal 24 and distal 26 colon sections nowjoined together. The staples 35, which are located circumferentiallyaround the colon tissue, are held securely in place by means of thecolon tissue walls, 25, 27 which have been reinforced with thebuttresses 12. The buttresses 12 provide circumferential support to theanastomotic junction in addition to enhancing sealing between thestaples and tissue. These buttresses 12 may therefore augment resistanceto radial distension at the anastomotic junction.

The above description relates to use of the buttresses 12 of the presentinvention in forming a tissue anastomosis in a colon resection. It isanticipated that buttresses of this design could be used for othergastro-intestinal applications, vascular applications and otherapplications in the human or animal body. Additionally, the abovedescription describes the buttresses 12 both being placed internallywithin the colon segments. In an alternative use, a buttress 12 could beplaced external to the colon segments. Further, buttresses 12 could beplaced internally within each colon segment while another buttress couldbe placed externally between the colon segments. In another use, onebuttress could be placed internally within one colon segment whileanother buttress could be placed externally between the colon segments.The number of buttresses 12 used and placement of the buttresses 12 inand around the relevant tissue sections is left to the surgeon.

The buttress 12 of the present invention may be fabricated from eitherbioabsorbable or non-absorbable biocompatible materials. A preferredembodiment for the buttress of the present invention is a bioabsorbableABA triblock copolymer of 67% PGA:33%TMC (w/w) formed into aself-cohering non-woven web as generally taught by Hayes in U.S. Pat.Nos. 6,165,217 and 6,309,423. Alternatively, this web or other buttressconstructs may be fabricated from other biocompatible bioabsorbablepolymers and copolymers composed from varying amounts of one or more ofthe following monomer examples: glycolide, d,l-lactide, I-lactide,d-lactide, p-dioxanone (1,4-dioxane-2-one), trimethylene carbonate(1,3-dioxane-2-one), ε-caprolactone, gamma.-butyrolactone,delta.-valerolactone, 1,4-dioxepan-2-one, and 1,5-dioxepan-2-one. Otherpolymeric constituents of a bioabsorbable copolymer may includepolyethylene glycol, polypropylene glycol, amino acids, anhydrides,orthoesters, phosphazines, amides, urethanes, and phosphoesters.Alternative copolymers may possess, in whole or in part, block,segmented, random, alternating, or statistical polymeric constructioncharacteristics. Animal derived products such as elastin, collagen ordecellularized submucosa, either absorbable (e.g. enzymatically degradedwithin the body) or rendered non-absorbable through chemical treatment(e.g., glutaraldehyde cross-linked bovine pericardium or porcinepericardium), may alternatively be utilized to provide a buttressconstruct. Various non-absorbable polymers may be utilized for buttressconstruction include but are not limited to polytetrafluoroethylene,fluorinated ethylene propylene (FEP), fluoroelastomers, polyurethanes,polyesters (e.g. polyethylene terephthalate), polyacrylamide,polyacetate, polypropylene, polydimethylsiloxane, and nylon. Of these,porous expanded polytetrafluoroethylene (ePTFE), generally made astaught by U.S. Pat. No. 3,953,566 to Gore, may provide a preferrednon-absorbable buttress.

A preferred method of forming the buttress 12 using a bioabsorbablematerial is using a piece of 67%/33% PGA:TMC (w/w) that has been formedinto a self-cohering non woven web into a thickness of approximately0.25 mm following methods as generally taught by Hayes in U.S. Pat. Nos.6,165,217 and 6,309,423. This piece of self-cohering non woven web iscut, for example, by a laser into a generally circular shape with anouter diameter made to coincide with the compression surface outerdiameters for the anvil 18 and body 20 of a particular circular stapler.A variety of other cutting methods, such as die cutting, can bealternatively used. Due to the porous construction of the self-coheringnon-woven web, various bioactive agents and carrier materials can beintroduced into the porous interfiber interstices of the web or coatedonto the fiber strands. Bioactive agents in this context refers togrowth factors, chemotactic factors, morphogens, pharmaceuticals ordrugs, catalysts, proteins, peptides or other biologically activemolecules or genetically altered or native state living cells ofautogenic, allogenic, xenogenic or recombinant origin that induce anintended biological response. Such substances include, but are notlimited to antibiotics, organic or inorganic antimicrobials, healingfactors, blood clotting agents, anticoagulants, antithrombotics,antispasmodics, immunosuppressives, antacids, acid inhibitors, and ulcertreating agents. Other fillers can include radiopaque substances toenhance visualization. Bioactive agents and fillers could be used withother porous and non-porous constructions for other bioabsorbable aswell as non-absorbable materials.

FIGS. 3A-3E show top views of buttresses 12 with various relief featurescut into them. These relief features form “adaptive openings” in thereinforcement material. These “adaptive openings” allow a largerdiameter anvil 16 of a circular surgical stapler 10 to be pulled throughthe smaller diameter opening created by the cutting blade of thecircular stapler without causing substantial permanent alteration to thereinforcement material. The relief features are preferably formed bylaser cutting, although they could be made by a variety of other methodssuch as by use of a cutting die. The relief features are sized andplaced so that some part of them remain on the portion of the buttress12 that remains in the patient after the cutting action of the blade ofa circular stapler. As will be further described, an adaptive openingmay also be provided by making the perimeter of the adaptive openingcorrugated, thereby providing extra material along the perimeter andaccordingly increasing its flexibility in order to allow the stapleranvil to be withdrawn through the adaptive opening.

FIG. 3A shows the top view of a buttress 12 with twelve equally spacedlinear radial cuts 32 emanating from the area of a central opening 30.

FIG. 3B shows the top view of a buttress 12 with four equally spacedlinear cuts or slits 34 in a radial spoke type pattern emanating fromthe area of a central opening 30.

FIG. 3C shows the top view of a buttress 12 with four equally spacedlinear cuts or slits 34 surrounding a central opening 30 as in FIG. 3Bbut with the addition of four radial cuts or slits 36 originating fromthe perimeter of the buttress 12.

FIG. 3D demonstrates that the relief features can be other than straightlines. FIG. 3D shows the top view of a buttress 12 that has serpentineshaped relief features 48 emanating from the area of a central opening30.

FIG. 3E demonstrates that other geometric figures could provide similarfunction to the operation of the buttress, showing the top view of abuttress 12 with a series of generally triangular shapes 40 that arearranged radially around a central opening 30. The bases of thetriangular shapes 42 are placed to coincide with the outside diameter ofthe generally circular concentric cutting blade of the selected circularstapler.

FIG. 3F shows a top view of a buttress 12 having a slit 51 through theentire width. It is apparent that, in addition to providing for anadaptive opening, the slit 51 allows the buttress 12 to be fitted overthe central shaft 14 of the stapler without necessitating the priorremoval of the anvil 16 from the stapler body 22.

FIG. 3G is a perspective view of a buttress 12 showing an embodimentwherein the adaptive opening results from corrugations 54. FIG. 3G hasan inner edge 50 and an outer edge 52 with corrugations 54 that areformed between the inner and outer edges 50, 52. These corrugations maybe made, for example, by transversely cutting a short segment from alength of tubular material, and deforming the resulting ring-shapedsegment by bending one edge inwardly to cause the inner hole whereby theextra material results in corrugations. Alternatively, a mold could beused to form the corrugations.

FIG. 3H is a perspective view of a buttress 12 showing an embodimentwherein the adaptive opening results from corrugations 54. FIG. 3H hasan inner edge 50 and an outer edge 52 with corrugations 54 that arepresent at the outer edge 52 but not at the inner edge 50. In analternate embodiment, the corrugations could be formed at the inner edge50, but not at the outer edge 52.

FIG. 3J is a perspective view of a buttress 12 showing an embodimentwherein the adaptive opening results from corrugations 54. FIG. 3J has acentral non-corrugated or planar region 56 with a corrugated area fromthe outer perimeter of the corrugated or planar region 58 to the outeredge of the buttress 52.

FIG. 3K is a perspective view of a buttress 12 showing an embodimentwherein the adaptive opening results from corrugations 54 of the innerregion of the buttress. FIG. 3K has an outer non-corrugated or planarregion 78 that surrounds the central region having corrugations 54.

In each of the buttresses depicted in FIGS. 3G, 3H, 3J, and 3K, theadaptive opening resulting from corrugations 54 are sized and placed sothat some part of the adaptive opening remains on the portion of thebuttress 12 that remains in the patient after the cutting action of theblade of a circular stapler.

It is anticipated that designs other than those depicted in FIGS. 3A-3H,3J and 3K may be used for the relief features on the buttresses 12.These various relief features allow for the anvil head 16 of a circularstapler 10 to pass through a buttress 12 without tearing orsubstantially altering the buttress 12, even though the anvil head 16compression surface 18 has an outer diameter larger than the innerdiameter of the hole formed in the buttress 12 when a generallycircular, concentric cutting blade of the circular stapler 10 has beenused to cut the hole in the buttress 12.

Self alignment of the buttress 12 onto a circular surgical stapler isanother important aspect of this invention. Self alignment insures thatthe buttress is generally aligned to coincide with and cover the patternof staples ejected from the stapler. The buttress 12 may be self-alignedusing an opening in its central region sized to closely fit the centralshaft of a circular stapler with which it is used. Alternatively, thebuttress 12 may be self-aligned using the outer diameter of the stapleranvil compression surface 18 and the outer diameter of the stapler bodycompression surface 20. FIGS. 3A-3H, 3J, 3K, 6A and 6B show buttresses12 adapted to self align using openings in their central regions. FIG.6A shows a perspective view of a buttress 12 which has an openingfeature 61 in its central region. FIG. 6B shows a cross section of thebuttress shown in FIG. 6A. Surface 60 in FIG. 6B contacts the outerdiameter of the central shaft 14 (FIG. 1B) of a circular stapler 10.FIG. 6C shows a perspective view of a buttress 12 which is adapted toself align onto the outer diameter of the stapler anvil compressionsurface 18 (FIG. 1B) or outer diameter of the stapler body compressionsurface 20 (FIG. 1B). FIG. 6D shows a cross section of the buttressshown in FIG. 6C. Surface 62 in FIG. 6D contacts the outer diameter ofthe stapler anvil compression surface 18 (FIG. 1B) or outer diameter ofthe stapler body compression surface 20 (FIG. 1B) to insure selfalignment.

The buttress 12 can be made of a constant thickness or can be made ofvarying thickness, densities or materials of construction through theircross sections. Varying thicknesses, densities or materials ofconstruction can be of advantage in some embodiments. For example,greater thickness or use of a denser material in the central region ofthe buttress would add rigidity, potentially aiding in self-aligning ofthe buttress 12 on the circular stapler 10. Thickness, density ormaterial variations may also help to prevent deformation of the buttress12 as the circular stapler is used in the process of pulling the stapleranvil 16 toward the stapler body 22 (as depicted in FIGS. 2B and 2C).This thicker or higher density material could be limited to the centralregion of the buttress so that the generally circular concentric cuttingblade of the stapler 10 would cut through or around this thickermaterial and remove it while the stapler was being withdrawn. In anotherembodiment, thinner or less dense material could be made to generallycoincide with the cutting diameter of the generally circular concentriccutting blade of the selected circular stapler to facilitate the cuttingprocess. Alternatively, thicker, more dense or stronger material couldbe constructed into the buttress 12 so as to coincide with the areaswhere the staples are placed with thinner, less dense or weaker materialused in other areas.

Three embodiments of buttresses 12 of varying cross sections are shownin FIGS. 4A-4C. FIG. 4A shows the side view of a buttress 12 that has asilicone disk 36 attached to it. The silicone disk 36 may beapproximately 0.5 mm thick, made, for example, with Nusil MED 4080(NuSil Technology, Carpinteria, Calif.) and can be provided with centerhole sized to form a slight interference fit with the central shaft 14of a circular stapler 10. The interference fit between the central shaft14 of the stapler and the center hole in the silicone disk 36 providesfor a means to securely fasten the buttress 12 to the circular staplerwithout an adhesive. The outer diameter of this silicone disk 36 issized to correspond with the central region of the buttress 12, fittingwithin the diameter of the generally circular concentric cutting bladeof a circular stapler 10.

One side of the silicone disc 36 is adhered to one side of the buttress12 by covering one side of the disc 36 with a thin coating of a pressuresensitive adhesive formulation of silicone (e.g., NuSil MED 1356, NuSilTechnology, Carpinteria, Calif.). After a 30 minute drying period, disc36 may be placed onto one surface of buttress 12 with the adhesivecoated surface of the silicone disk 36 facing towards the surface of thebuttress 12 as illustrated in FIG. 4A. Compressive force is then appliedto the silicone disk 36 to assure adequate bonding between of thesilicone disk 36 to the buttress 12.

Other means of making the central section of the buttress 12 thicker maybe used, such as using materials other than silicone or building up moreself-cohering non-woven web thickness.

FIG. 4B shows the side view of a buttress 12 where the central region 37is thicker due to the process of adding more material to the centralregion in comparison to the thickness adjacent the perimeter. FIG. 4Cshows the top view of a buttress 12 where the central section 42 is madewith thicker or higher density material. Spokes 44 emanating from thecentral section 42 are also made with thicker or higher densitymaterial. A perimeter area 46 of the buttress 12 as depicted can also bemade with a thicker or higher density material to increase the strengthof the material for staple reinforcement. The buttresses 12 depicted inFIGS. 3A-3E and 4A-4C and other designs that can be contemplated mayalso be constructed in a modular fashion such that individual materialscan be combined to form the final device.

Additionally, buttresses 12 of various designs including those depictedin FIGS. 3A-3H, 3J, 3K, and 4A-4C can be used with a circular staplerthat has a round or non-round central shaft. Circular staplers withnon-round shafts with buttresses 12 having central openingscorresponding to the shape of the shaft could facilitate indexing of thebuttresses 12 to locations relative to the stapler anvil and bodycompression surfaces 18 and 20.

A buttress 12 can be constructed to exhibit either essentially elasticor essentially inelastic behavior. Essentially elastic behavior occurswhen a buttress 12 is adequately deformable so as to allow an anvil head16 of larger outer diameter to pass through the smaller diameter openingformed in the buttress 12 by the circular stapler cutting blade withoutcausing permanent alteration or damage to the cut edge of the openingformed by the cutting action of the circular stapler blade. Permanentalteration of the cut edge results from tears, rips, or other permanentdeformation. Essentially inelastic behavior occurs when an anvil head 16of larger outer diameter than the smaller diameter opening formed in abuttress 12 by the circular stapler cutting blade causes permanentalteration or damage to the cut edge of the opening formed by thecircular stapler cutting blade. The essentially inelastic buttress 12 bydefinition would rip, tear, or otherwise retain permanent alteration tothe cut edge of the opening formed by the circular stapler cutting bladeafter passing the larger diameter anvil head 16 through the smalleropening formed by the circular stapler cutting blade. A buttress may bemade from either relatively elastic (e.g., silicone) or relativelyinelastic materials (e.g., PGA:TMC). If made from relatively inelasticmaterials, the buttress may be fabricated in such a way as to nowpossess essentially elastic behavior. For example, inelastic materialsmay be fabricated into a material possessing a degree of porosity, suchas a weave or a web, wherein the porosity provides for adequateflexibility thereby allowing the resulting buttress to demonstrateessentially elastic behavior.

The relief features shown in FIGS. 3A-3H, 3J and 3K as well as otherscan be used with either essentially elastic or essentially inelasticbuttresses 12. These relief features will be required, however, forbuttresses 12 that without such relief features would exhibitessentially inelastic behavior.

FIG. 5A shows the top view of a buttress 12 which has a central opening30 sized to closely fit the outside diameter of a central tubular shaft14 of a circular stapler 10. FIG. 5B shows the top view of a buttress 12after a hole with a cut edge 38 has been cut through it by the action ofa generally circular concentric cutting blade of a circular stapler 10.FIG. 5C shows the top view of a buttress 12 constructed to be elasticafter a circular stapler anvil head 16 with a compression surface 18that has an outer diameter larger than the diameter of the cut edge 38of the opening formed by the action of a generally circular concentriccutting blade has been passed through it. No substantial permanentalteration or damage is made to the cut edge 38 of the opening formed bythe generally circular concentric cutting blade of the circular stapler.

FIGS. 5D, 5E and 5G show the top and side views of buttresses 12 thatare inelastic and without relief features such as shown in FIGS. 3A-3H,3J and 3K, after pulling through a circular stapler anvil head 16 with acompression surface 18 that has an outer diameter larger than thediameter of the cut edge 38 of an opening formed by the action of agenerally circular concentric cutting blade. These buttresses 12 showsubstantial permanent alteration or damage to the cut edge 38 area ofthe opening formed by the action of a generally circular concentriccutting blade of a circular stapler 10. FIG. 5D of an inelastic buttress12 shows tears 48 around the cut edge 38 of the opening caused bypulling through a circular stapler anvil head 16 with a compressionsurface 18 that has a larger diameter than that of the opening. FIGS. 5Eand 5G of an inelastic buttress 12 show deformation 49 around the cutedge 38 of the opening caused by pulling through a circular stapleranvil head 16 with a compression surface 18 that has a larger diameterthan that of the opening. Other modes of substantial permanentalteration or damage of the cut edge 38 can be contemplated.

In order to evaluate the compatibility of buttresses of the presentinvention with circular staplers, two buttresses of 67% PGA:33% TMC(w/w) having a web density of about 0.5 g/cc. These buttresses were madeto have a circular shape with an outside diameter of approximately 30mm, for use with a circular stapler (ILS 29 mm, Ethicon Endosurgery,Somerville N.J.). The buttresses were of uniform thickness of about 0.25mm, and were provided with a center hole of about 6.3 mm diameter. Thecentral region of each buttress was also provided with a circularsilicone stiffener having a diameter of about 19.1 mm and a thickness ofabout 0.5 mm. Each of these stiffeners was provided with a 6.3 mmdiameter hole at its center. One stiffener was adhered to one side ofeach buttress with the center holes through each component aligned,using MED-1356 silicone adhesive, Nusil technologies, Carpenteria Calif.

A 30 cm section of porcine colon was obtained and cut in half; pursestring sutures were made on adjacent ends of the large bowel sections.The anvil, with first buttress in place with the stiffener facing thestapler body, was fed through one section so that the anvil postprotruded through the hole in the purse-stringed end. The stapler body,with the shaft extended and with the second buttress in place with thestiffener facing the anvil, was advanced through the adjacent colontissue until the post protruded through the purse-stringed hole. Theanvil post was mated to the body shaft and closed via the actuator knobon the proximal end of the device according to the manufacturer'sinstructions for use. After firing the stapler and rotating the actuatorknob two full turns, the stapler was rotated 90 degrees relative to theanastomosis in both directions and then removed from the colon tissue,pulling the anvil through the anastomosis. Both sides of the anastomosiswere observed visually for integrity of the buttresses after removingthe anvil (of 28.6 mm outside diameter) through the cut hole (of 20.8 mmdiameter). All staples on both sides of the anastomosis were capturedand no signs of tearing or disfigurement were observed.

An additional pair of buttresses was fabricated and tested in the samemanner. Each buttress of this additional pair was provided with fourslits through the thickness of the material, spaced 90 degrees apart andextending radially outward from a point 1.9 mm from the edge of thecenter hole for a length of 7.6 mm. During testing, this pair wasdetermined to be equally effective as the first pair.

While the principles of the invention have been made clear in theillustrative embodiments set forth herein, it will be obvious to thoseskilled in the art to make various modifications to the structure,arrangement, proportion, elements, materials and components used in thepractice of the invention. To the extent that these variousmodifications do not depart from the spirit and scope of the appendedclaims, they are intended to be encompassed therein.

1. A reinforcement device for use with a circular stapler that isadapted to create and seal a surgical opening in a patient comprising: abuttress adapted for mounting on the circular stapler, the staplerhaving an anvil that is larger in diameter than the surgical openingthat is created by the stapler, wherein following stapling with thestapler, the buttress reinforces the surgical opening created by thestapler in the patient; wherein the buttress includes at least oneadaptive opening created by the circular stapler which corresponds tothe surgical opening in the patient, said adaptive opening when circularhaving a diameter smaller than the diameter of the anvil, and whereinthe adaptive opening in the buttress allows the anvil to be removedtherethrough without causing permanent alteration to the buttress. 2.The reinforcement device of claim 1 wherein the permanent alterationincludes tearing.
 3. The reinforcement device of claim 1 wherein thepermanent alteration includes permanent deformation to the adaptiveopening created by the stapler.
 4. The reinforcement device of claim 1wherein the buttress has slits along a periphery of the adaptiveopening.
 5. The reinforcement device of claim 1 wherein the buttress iscorrugated along a periphery of the adaptive opening.
 6. Thereinforcement device of claim 1 wherein the buttress self-aligns on thestapler.
 7. The reinforcement device of claim 6 wherein the self-alignedbuttress is retained on the stapler without use of an adhesive.
 8. Thereinforcement device of claim 6 wherein the buttress self-aligns withrespect to a central shaft on the stapler.
 9. The reinforcement deviceof claim 6 wherein the buttress self-aligns on the stapler by conformingto an edge delimiting an outer diameter of the stapler.
 10. Thereinforcement device of claim 1 wherein the reinforcement buttresscomprises a bioabsorbable material.
 11. The reinforcement device ofclaim 10, wherein the bioabsorbable material comprises a copolymer ofpoly(glycolide:trimethylene carbonate).
 12. The reinforcement device ofclaim 1 wherein the buttress includes a filler material.
 13. Thereinforcement device of claim 12 wherein the filler material comprises atherapeutic agent.
 14. The reinforcement device of claim 12 wherein thefiller material comprises a bioactive agent.
 15. The reinforcementdevice of claim 1 wherein the buttress comprises an essentiallyinelastic material.
 16. The reinforcement device of claim 1 wherein thebuttress comprises an essentially elastic material.
 17. Thereinforcement device of claim 1 wherein the buttress comprises at leastone polymeric material.
 18. The reinforcement device of claim 17 whereinthe polymeric material comprises polytetrafluoroethylene.
 19. Thereinforcement device of claim 18 wherein the polytetrafluoroethylene isporous expanded polytetrafluoroethylene.
 20. The reinforcement device ofclaim 1 wherein the circular stapler is adapted to create an anastomoticjunction between body tissue; and the buttress augments resistance toradial distension at the anastomotic junction.
 21. The reinforcementdevice of claim 1 wherein the device has a reinforced central regionthat provides added rigidity to the central region.
 22. Thereinforcement device of claim 21 wherein the central region has greaterthickness than other regions of the device.
 23. The reinforcement deviceof claim 21 wherein the central region has denser material than otherregions of the device.
 24. A reinforcement device for use with acircular stapler that is adapted to create a substantially circular holein a patient, said circular stapler having a central shaft, comprising:a buttress adapted for mounting on the central shaft of the circularstapler; wherein the buttress self-aligns around the central shaft; andwherein the buttress reinforces the hole created by the stapler in thepatient.
 25. The reinforcement device of claim 24 wherein the staplerincludes an anvil that is larger in diameter than the circular hole thatis created by the stapler.
 26. The reinforcement device of claim 24wherein the buttress comprises an essentially elastic material.
 27. Thereinforcement device of claim 24 wherein the buttress comprises anessentially inelastic material.
 28. The reinforcement device of claim 24wherein the buttress comprises at least one polymeric material.
 29. Thereinforcement device of claim 28 wherein the polymeric materialcomprises polytetrafluoroethylene.
 30. The reinforcement device of claim29 wherein the polytetrafluoroethylene is porous expandedpolytetrafluoroethylene.
 31. The reinforcement device of claim 24wherein the buttress comprises a bioabsorbable material.
 32. Thereinforcement device of claim 31, wherein the bioabsorbable materialcomprises a copolymer of poly(glycolide:trimethylene carbonate).
 33. Thereinforcement device of claim 24 wherein the buttress includes a filler.34. The reinforcement device of claim 33 wherein the filler includes atherapeutic agent.
 35. The reinforcement device of claim 33 wherein thefiller includes a bioactive agent.
 36. A reinforcement devicecomprising: a circular stapler that is adapted to create a substantiallycircular hole in a patient, said circular stapler having a stapler anvilcompression surface outer diameter and a stapler body compressionsurface outer diameter; a first buttress adapted to self align onto thestapler anvil compression surface outer diameter and the stapler bodycompression surface outer diameter; a second buttress adapted to selfalign onto the stapler body compression surface outer diameter; andwherein the first and second buttresses reinforce the hole created bythe stapler in the patient when staples are applied.
 37. Thereinforcement device of claim 36 wherein the stapler includes an anvilthat is larger in diameter than the circular hole that is created by thestapler.
 38. The reinforcement device of claim 36 wherein the buttresscomprises an essentially elastic material.
 39. The reinforcement deviceof claim 36 wherein the buttress comprises an essentially inelasticmaterial.
 40. The reinforcement device of claim 36 wherein the buttresscomprises at least one polymeric material.
 41. The reinforcement deviceof claim 40 wherein the polymeric material comprisespolytetrafluoroethylene.
 42. The reinforcement device of claim 41wherein the polytetrafluoroethylene is porous expandedpolytetrafluoroethylene.
 43. The reinforcement device of claim 36wherein the buttress comprises a bioabsorbable material.
 44. Thereinforcement device of claim 43, wherein the bioabsorbable materialcomprises a copolymer of poly(glycolide:trimethylene carbonate).
 45. Thereinforcement device of claim 36 wherein the buttress includes a filler.46. The reinforcement device of claim 45 wherein the filler includes atherapeutic agent.
 47. The reinforcement device of claim 45 wherein thefiller includes a bioactive agent.
 48. A reinforcement devicecomprising: a circular stapler that is adapted to create a substantiallycircular hole in a patient, said circular stapler having a stapler anvilcompression surface outer diameter at least one buttress adapted to selfalign onto the stapler anvil compression surface outer diameter; andwherein the buttress reinforces the hole created by the stapler in thepatient when staples are applied.
 49. The reinforcement device of claim48 wherein the stapler includes an anvil that is larger in diameter thanthe circular hole that is created by the stapler.
 50. The reinforcementdevice of claim 48 wherein the buttress comprises an essentially elasticmaterial.
 51. The reinforcement device of claim 48 wherein the buttresscomprises an essentially inelastic material.
 52. The reinforcementdevice of claim 48 wherein the buttress comprises at least one polymericmaterial.
 53. The reinforcement device of claim 52 wherein the polymericmaterial comprises polytetrafluoroethylene.
 54. The reinforcement deviceof claim 53 wherein the polytetrafluoroethylene is porous expandedpolytetrafluoroethylene.
 55. The reinforcement device of claim 48wherein the buttress comprises a bioabsorbable material.
 56. Thereinforcement device of claim 55, wherein the bioabsorbable materialcomprises a copolymer of poly(glycolide:trimethylene carbonate).
 57. Thereinforcement device of claim 48 wherein the buttress includes a filler.58. The reinforcement device of claim 57 wherein the filler includes atherapeutic agent.
 59. The reinforcement device of claim 57 wherein thefiller includes a bioactive agent.
 60. A reinforcement devicecomprising: a circular stapler that is adapted to create a substantiallycircular hole in a patient, said circular stapler having a stapler bodycompression surface outer diameter at least one buttress adapted to selfalign onto the stapler body compression surface outer diameter; whereinthe buttress reinforces the hole created by the stapler in the patientwhen staples are applied.
 61. The reinforcement device of claim 60wherein the stapler includes an anvil that is larger in diameter thanthe circular hole that is created by the stapler.
 62. The reinforcementdevice of claim 60 wherein the buttress comprises an essentially elasticmaterial.
 63. The reinforcement device of claim 60 wherein the buttresscomprises an essentially inelastic material.
 64. The reinforcementdevice of claim 60 wherein the buttress comprises at least one polymericmaterial.
 65. The reinforcement device of claim 64 wherein the polymericmaterial comprises polytetrafluoroethylene.
 66. The reinforcement deviceof claim 65 wherein the polytetrafluoroethylene is porous expandedpolytetrafluoroethylene.
 67. The reinforcement device of claim 60wherein the buttress comprises a bioabsorbable material.
 68. Thereinforcement device of claim 67, wherein the bioabsorbable materialcomprises a copolymer of poly(glycolide:trimethylene carbonate).
 69. Thereinforcement device of claim 60 wherein the buttress includes a filler.70. The reinforcement device of claim 69 wherein the filler includes atherapeutic agent.
 71. The reinforcement device of claim 69 wherein thefiller includes a bioactive agent.